Offer animation - Blender or some other program
Blender is good for this type of presentations. 

You can make video like this:
https://www.youtube.com/watch?v=L__2suWPk9s 

or interactive 3D-presentations like this (using addon blend4web): https://www.blend4web.com/apps/dairy_plant/dairy_plant.html?v=9e5dd2c40ed17b48ebd949bf7f8d9d0c